No. 3. — Contributions from the Zoological Zahoratory of the 

 3fuseum of Comparative Zoology at Harvard College, under 

 the direction of E. L. Mark, No. 126. 



THE REGENERATING NERVOUS SYSTEM OF LUMBRTCID.E 

 AND THE CENTROSOME OF ITS NERVE CELLS. By Herbert 

 W. Rand. 



TABLE OF CONTENTS. 



PAGE 



I. Introduction 86 



II. Historical 87 



1. Tlie Centrosome in Nerve 



Cells 87 



2. The Centrosome in Other 



Resting Cells .... 96 



III. Methods of Investigation . 102 

 L Material 103 



2. Regeneration Methods . 104 



3. Fixing Fluids .... 105 



4. Stains 107 



5. Drawings 108 



IV. Observations 109 



1. The Nerve Cells of Lum- 



bricidas 109 



a. The Nuclei .... 110 



b. The Cytoplasm ... Ill 



c. The Centred System . 112 



2. The Nerve Cells of Nereis 115 



3. Outline of the Process 



of Regeneration of the 

 Brain and Anterior Gan- 

 glia 115 



4. Origin of the Cells of the 



Nervous Fundaments . 118 



5. Histology of the Nervous 



Fundaments .... 122 

 TOL. XXXVII. — NO. 3 



PAOB 



6. Mitosis in the Nervous 



Fundaments .... 125 



7. Development of the Nerve 



Cells 130 



8. The Centrosome in the 



Mature Regenerated 

 Nerve Cells .... 135 

 V. General Conclusions . . . 136 



1. Mitosis in the Nervous 



Fundaments .... 136 



2. Development of the 



Nerve Cells 137 



3. Persistence of the Centro- 



some 139 



4. The Centrosome in Nerve 



Cells 140 



VI. The Centrosome in Cells of 



the Epidermis .... 144 

 VII. Mitosis in the Regenerating 



Epidermis 146 



VIII. Mitosis in the Subepidermal 

 Cells of the Old Epider- 

 mis 148 



IX. Some Peculiar Mitoses . . 149 



X. Summary 151 



Literature cited 155 



Explanation of Plates 164 



